The barbed knife ripped through the girl's throat. Her body slumped to the cold flagstones, her dark hair settling on the pool of blood before her. Reflections writhed on the slick, crimson surface as the chill mountain winds pulled and twisted at the flames of the courtyard torches. The old woman made herself watch as the girl died. Then she raised her eyes to the man holding the blade.

The soldiers had left. Thirty of her kin lay dead. She and this man were the only living things that remained in this castle, on this mountain. An old woman, a bloodied warrior, and the knife.

"Get up, babă," the man said, roughly. He took her arm and pulled her to her feet.

He spoke her language, she realised with a start. He had used another tongue with the soldiers, harsh to her ears. But through all of the killing, he had been silent; his movements had been ritual, but deft and efficient. Beyond her horror, she could even see a beauty in them. The thought made her sick.

The man turned her to face him, still gripping her wrist. "Look at me, babă. Do you know me?"

She saw his coal-black hair and olive skin. His lithe figure, stripped to the waist and smeared with drying blood. She looked into his dark eyes, burning. The terror pooling in her stomach grew deeper and thicker.

She broke her gaze. "The rumours say you are called the Dragon's Son," she said, voice low.

The warrior inclined his head in acknowledgement. "I have a task for you, grandmother." The diminutive was laced with casual contempt.

She had expected death, another body amid the slaughter. The idea that he would spare her, the eldest of her family, felt cruel and mocking. Her jaw tensed as her fear mingled with new emotions - hatred, confusion and, underneath it all, a small but defiant hope.

If he felt that tension in her, that hope, the man did not show it. He dropped her wrist.

"Leave this place," he continued. "Go, and tell your people what you have seen tonight. They will respect your words. Tell them that I am real. Tell all of the Romani that Wallachia has a new prince, and that they shall serve me, or bleed."

She looked at the scarlet fingerprints he had left on her wrist, and her anger flared.

"The Roma do not serve. We have no princes," she said fiercely.

But the warrior laughed at her.

"Do you think you are the first to say that? I have broken warriors and enslaved cities. I have travelled here with fifty men, and I will rule Wallachia within the year. I shall carve up Moldavia and Transylvania like roasting lambs. The Ottomans will fear me, and fall before me. You gypsies are nothing."

"Yet the Roma will not serve." It was the stubbornness of long years, crowding out her dread.

"Then I will show you the cost," the warrior said.

He reached toward her face, faster than she could react, and she felt his fingers rub blood - still wet, still warm - across her eyelids. The world spun, and her eyes opened on a rust-coloured nightmare.

She was looking down on an army encampment, which grew ever closer. The moon's light was garnet and ruby, the shadows black. She fell nearer to the soldiers, spying their turbans and scimitars. Suddenly, tents across the camp were ablaze, sending men and horses into a panic. As the fires roared, dark figures raced between them, slaughtering the confused soldiers. At their head, the warrior's face was lit by flames and bloody moonlight.

Then the vision was gone, and she was walking through a dense forest, the light still red. She felt pulled forward, inexorably. As she squeezed through the mass of tall, bare trunks, a drop of liquid on her shoulder drew her gaze upward. Upward, to the corpses hanging over her.

There were no trees. She was in a forest of stakes, a thicket of the impaled. Men, women, children: hundreds of bodies, thousands - she could see no end to them. They hung slack from the poles driven through them from every angle, sharpened points protruding from mouths, necks, limbs, bellies. The sheer weight of them looming above staggered her, but she kept walking, drawn forward despite herself.

Blood dripped steadily from above as her weakened legs led her up a small rise. She emerged from the forest of the dead into a clearing, and saw the warrior. He was standing at the crest of the hill, a young girl in white on a stone slab before him. From all directions, streams of blood were flowing up the hill towards him, gathering in a pool at his feet. The stakes stretched around in every direction, death as far as she could see. The warrior leaned down and grasped the girl, and as he bit into her neck, his eyes flicked up and met the old woman's.

And then she was back in the courtyard, in the cold night. The warrior looked at her imperiously.

"Dhampir!" she cursed. "Blood demon!"

She pulled a wooden crucifix from her belt and thrust it towards him, her other hand fumbling in her pockets. The warrior spread his hands wide. As she advanced, he stepped cautiously backwards, stopping with his feet in the pool of blood.

She hesitated, and again he laughed. A swift gesture from the warrior, and the crucifix snapped in her hand, the arms of the crosspiece falling to the flagstones. The Christ-figure had been twisted and distended, with the stipe of the cross now impaling it from groin to crown.

The old woman dropped the defiled cross - in any case, it had been merely a distraction. Her other hand emerged from her skirt with a mix of preserved leaves, which she blew towards the warrior. Suspended in the air, they swirled thicker and faster, enveloping the man in a disorienting cloud of debris. He ducked downwards, doubled over, but the miniature whirlwind moved with him, cutting off sight and sound.

The woman fell back, looking for an escape. Even as she retreated, she saw the blood rise from the ground. A wave of it soaked the leaves and washed them to the ground, and the warrior rose, striding forward. Blood hung in the air in sheets behind him, like great red wings.

"Herb witch," he snarled. "Do you think your dirt magic can touch a host-lord of the Daeva?"

He waved a hand, and she could not move. He closed the gap between them, swinging the knife. The flat of the blade caressed her cheek as it passed her head. Then it was still and poised in his hand, the point towards her face.

The warrior continued, "Our empire stretches from Kalmar to the Siberian wastes. I am the spearhead - through me the Daeva shall conquer West and East, onwards without limit. You and your people are ashes before the wind of our coming."

He brought the dagger slowly in, pushing nearer. Her throat thickened, but she could not scream. Her world narrowed to the size of the knife, to the size of the point. Still it came closer. She felt the tip resting on the surface of her eye.

"You cannot choose but serve," the man said, his voice grown quiet. "Only the manner of your service is within your power. Tell your people - they will be slaves, or they will be cattle."

The knife stopped. She could not blink. The point on her eyeball was worse than pain - every nerve in her body was focussed on the pressure, willing it not to increase, imagining that it had.

The Daeva lord leaned in close to her motionless head, and whispered, "That girl, the last I killed. She was your granddaughter, yes? I could taste it in her. Think on her before you answer. Think on her sister. On all of your family."

Her realisation was abrupt - she had one last, desperate hope. She pulled at her memories for scraps of forbidden knowledge, that only long years of training with her own grandmother had taught her to resist. Suddenly he released the hold that was on her; she wrenched her head away from the knife, and he smiled and threw it high. The old woman gathered herself, turning back to the warrior.

"The Roma do not serve." She spat at his feet.

His swiftness was beautiful and savage. One hand grabbed her arms, the other plucked the dagger from the air. Blood sprayed from her wrists as the barbs tore them open. Her hands hung limp, and pain and shock overtook her.

The Daeva's hand was a vice on her arms. "I will not make this quick for you," he said, and bent to drink from her severed veins.

As she stood, dying, the old woman gave a keening wail: for her daughter, for her daughter's daughter, for all her kin. Her voice wavered into a thin, wordless tune, discordant as the crows that roosted in the castle towers.

She had only sung for a short time before the warrior cut her throat.

But it was long enough.

When Konstantin, janissary of His Imperial Majesty Mehmet II, climbed with his guards the thousand steps to Poenari Citadel, he had not believed the stories they told in Sibiu. But the grisly scene in the courtyard was beyond his ability to explain.

Close to a hundred bodies, dead for at least a month but untouched by wolves or carrion birds. Some hung upside down from the walls, their throats slashed open like butchered pigs. Others lay in piles, naked and pallid, their skin ribboned by hundreds of deep cuts, as if to bleed them from every scrap of flesh. Many of the corpses appeared to be gypsies. The rest were like no people known to the Ottoman Empire - wild-haired and tattooed, with devilish-looking weapons, oddly undrawn. But even this was not what had daunted him.

Almost every surface of the courtyard was painted with blood. The recent rains had streaked it into illegibility, but it must have been monumental: perhaps a mural, or notation in a language with which Konstantin was not familiar. But it was impossible, unthinkable. For what great work would all these people bleed?

As he passed another heap of corpses, Konstantin spied a lone figure slumped against the far wall. A pool of blood had clearly dried beneath the body, but the wall next to it was the only clean surface in the entire courtyard.

Konstantin, walking closer, saw a man with olive skin and a fighter's build. The warrior's face was smudged with faded red, with deep scratches down each side from sharpened fingernails: the man's own nails, Konstantin could see the blood beneath them. His eyes were open in a fervid stare at that last blank piece of stone. His left arm was covered in wounds - the tip of one finger cut off, the palm of the hand slashed across. The left wrist was almost severed by a single deep cut; it was pressed against the edge of the empty wall in a final faltering smear. And his right hand still gripped the barbed knife.

Konstantin climbed back down the thousand steps, his thoughts troubled. But as he descended, the soft Transylvanian rains returned. The tide of history ebbed, and his memories of the Daeva were washed away. By the time he reached the valley floor, he had forgotten his purpose there, and he once again felt sanguine.